The present invention relates to a laminated board which includes a layer of porous, expanded polytetrafluoroethylene (E-PTFE).
Regarding printed circuit boards using E-PTFE sheets of this type, the present inventors have disclosed the concept of lamination in Japanese Laid-Open Model Application (Kokai) No. 62-49277 and Japanese Laid-Open Utility Model Application (Kokai) No. 62-65879). In those applications, however, the porous material was used "as is". As a result, great care and skill were required for the working of the material, and the electrical characteristics tended to be unpredictable.
The present invention was developed in order to solve the abovementioned problems encountered in prior technology. An object of the present invention is to provide, with greater efficiency, a laminated board for printed circuit board use which has stable and predictable electrical characteristics and which does not require great skill to manufacture.